<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <p>1111</p>
    <div>222</div>
    <style>
    p{
        color: red ;
    }
    p{
        color: red;
        opacity: 0.5;
    }
    div{
        width: 200px;
        height: 200px;
        border: 10px solid silver;
        box-shadow: 5px 4px 10px 2px gray;
    }
    div{
        width: 200px;
        height: 200px;
        border: 10px solid red;
        outline: 10px double red;
    }
    div{
        cursor: move;
    }
    div{
        border-radius: 50px;
    }
    div{
        -webkit-border-radius:50px;
        -moz-border-radius:50px;
        border-radius: 50px;
    }
    div{
        border-radius: 50px;
        -webkit-border-radius:100px ;
    }
    </style>
    <h1>标题</h1>
    <p>我是一个段落<code>代码</code></p>
    <style>
    html{
        font-size: 62.5%;
    }
    h1{
        font-size: 3em;
    }
    p{
        font-size: 1.4em;
    }
    code{
        font-size: 8rem;
    }
    </style>
</body>
</html>